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52 pages, 1395 KB  
Review
Heterogeneous Integration Technology Drives the Evolution of Co-Packaged Optics
by Han Gao, Wanyi Yan, Dan Zhang and Daquan Yu
Micromachines 2025, 16(9), 1037; https://doi.org/10.3390/mi16091037 - 10 Sep 2025
Abstract
The rapid growth of artificial intelligence (AI), data centers, and high-performance computing (HPC) has increased the demand for large bandwidth, high energy efficiency, and high-density optical interconnects. Co-packaged optics (CPO) technology offers a promising solution by integrating photonic integrated circuits (PICs) directly within [...] Read more.
The rapid growth of artificial intelligence (AI), data centers, and high-performance computing (HPC) has increased the demand for large bandwidth, high energy efficiency, and high-density optical interconnects. Co-packaged optics (CPO) technology offers a promising solution by integrating photonic integrated circuits (PICs) directly within or close to electronic integrated circuit (EIC) packages. This paper explores the evolution of CPO performance from various perspectives, including fan-out wafer level packaging (FOWLP), through-silicon via (TSV)-based packaging, through-glass via (TGV)-based packaging, femtosecond laser direct writing waveguides, ion-exchange glass waveguides, and optical coupling. Micro ring resonators (MRRs) are a high-density integration solution due to their compact size, excellent energy efficiency, and compatibility with CMOS processes. However, traditional thermal tuning methods face limitations such as high static power consumption and severe thermal crosstalk. To address these issues, non-volatile neuromorphic photonics has made breakthroughs using phase-change materials (PCMs). By combining the integrated storage and computing capabilities of photonic memory with the efficient optoelectronic interconnects of CPO, this deep integration is expected to work synergistically to overcome material, integration, and architectural challenges, driving the development of a new generation of computing hardware with high energy efficiency, low latency, and large bandwidth. Full article
(This article belongs to the Special Issue Emerging Packaging and Interconnection Technology, Second Edition)
21 pages, 3464 KB  
Article
A Hypoglycemic Peptide from Pinus pumila Nut Oil Meal Improves Glycolipid Metabolism via Multi-Dimensional Regulation in Type 2 Diabetic Mice
by Zhe-Xuan Mu, Zhen-Zhou Li, Bing-Xiao Liu, Zhen-Yu Wang, Xiao-Hong Lv, Lin Yang and Hua Zhang
Nutrients 2025, 17(17), 2903; https://doi.org/10.3390/nu17172903 - 8 Sep 2025
Abstract
Background and Methods: To address the need for dietary interventions in sub-healthy populations and promote sustainable utilization of agricultural by-products, we isolated Pinus pumila hypoglycemic peptide (PHP) from nut oil meal through enzymatic extraction, ion exchange and gel chromatography purification, and simulated gastric [...] Read more.
Background and Methods: To address the need for dietary interventions in sub-healthy populations and promote sustainable utilization of agricultural by-products, we isolated Pinus pumila hypoglycemic peptide (PHP) from nut oil meal through enzymatic extraction, ion exchange and gel chromatography purification, and simulated gastric digestion. Results: PHP exhibited significant inhibitory activity against α-amylase and α-glucosidase. In type 2 diabetic mice, PHP significantly ameliorated the “three-more-one-less” syndrome, reduced glycosylated hemoglobin and insulin levels, mitigated liver and kidney tissue lesions, and improved glucose and lipid metabolic disorders—effects partly supported by its enhancement of intestinal barrier function via restoring gut microbiota diversity. Gut microbiota analysis revealed that PHP exerts hypoglycemic effects by regulating gut microbial composition: increasing SCFA-producing taxa, reducing pro-inflammatory/metabolic disorder-associated taxa, and normalizing the Firmicutes/Bacteroidetes ratio. KEGG pathway analysis demonstrated that PHP mediates synergistic hypoglycemic effects by regulating carbohydrate metabolism, amino acid metabolism, and cofactor/vitamin metabolism. Conclusions: This work provides a theoretical foundation for developing natural functional foods from agricultural by-products, supporting PHP’s potential as a dietary supplement for metabolic regulation. Full article
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20 pages, 14858 KB  
Article
Hydrochemistry and Geothermal Potential of Żary Pericline (SW Poland)
by Barbara Kiełczawa
Water 2025, 17(17), 2647; https://doi.org/10.3390/w17172647 - 7 Sep 2025
Viewed by 910
Abstract
The mineralization of groundwater within the Żary pericline exhibits a broad range, from 0.2 to 0.3 g/L up to 401 g/L, with the majority classified as brines. These waters are predominantly chloride-rich, characterized by variable concentrations of cations such as Na+, [...] Read more.
The mineralization of groundwater within the Żary pericline exhibits a broad range, from 0.2 to 0.3 g/L up to 401 g/L, with the majority classified as brines. These waters are predominantly chloride-rich, characterized by variable concentrations of cations such as Na+, K+, Ca2+, and Mg2+. Their chemical composition varies by geological formation: Na-Cl and Mg-Cl types dominate in the Triassic strata, while more complex mixtures are observed in the Zechstein and Rotliegend formations. Brine formation and evolution are primarily influenced by evaporation and ion exchange processes, particularly Na+/Ca2+ exchange. These brines represent residual evaporative fluids that migrate through the subsurface during sediment compaction and tectonic deformation. The observed variability in mineral content suggests the occurrence of hydrochemical inversion within the geological layers. Groundwater temperatures range from 20 °C to 55 °C at depths between 490 and 1525 meters below ground level. The geothermal gradient spans from 3.55 °C/100 m to 4 °C/100 m, with the highest values recorded in the western and northwestern sectors of the pericline. These thermal conditions indicate promising potential for geothermal energy development in the region. Full article
(This article belongs to the Section Hydrogeology)
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17 pages, 2631 KB  
Article
Adsorption of Phosphates from Wastewater Using MgAlFe-Layered Double Hydroxides
by Oanamari Daniela Orbuleţ, Liliana Bobirică, Mirela Enache (Cişmaşu), Ramona Cornelia Pațac, Magdalena Bosomoiu and Cristina Modrogan
Environments 2025, 12(9), 316; https://doi.org/10.3390/environments12090316 - 7 Sep 2025
Viewed by 315
Abstract
Phosphates pollution, primarily from agricultural runoff and wastewater discharge, is a major contributor to water eutrophication, adversely affecting aquatic ecosystems. This study reports the synthesis, characterization, and phosphates adsorption performance of a MgAlFe-layered double hydroxide (MgAlFe-LDH) with a 2:1:1 cationic ratio. The material [...] Read more.
Phosphates pollution, primarily from agricultural runoff and wastewater discharge, is a major contributor to water eutrophication, adversely affecting aquatic ecosystems. This study reports the synthesis, characterization, and phosphates adsorption performance of a MgAlFe-layered double hydroxide (MgAlFe-LDH) with a 2:1:1 cationic ratio. The material was prepared via co-precipitation and characterized using digital microscopy, XRD, BET, XPS, and FTIR. Adsorption experiments were conducted at pH 3 and 9 to investigate equilibrium, kinetics, and reusability. The MgAlFe-LDH exhibited a high maximum adsorption capacity (q_max ≈ 215 mg/g) largely independent of pH, with adsorption well described by the Langmuir model. Kinetic studies revealed a pseudo-first-order mechanism, indicating that adsorption is dominated by surface diffusion and electrostatic interactions. Phosphate removal occurs through a dual mechanism involving rapid electrostatic attraction at protonated surface sites and slower ion exchange in the LDH interlayers. The material retained over 75% of its adsorption capacity after five consecutive adsorption–desorption cycles, highlighting its potential for sustainable phosphate recovery. Overall, the MgAlFe-LDH represents a promising, reusable adsorbent for phosphorus removal from wastewater, supporting circular economy strategies. Full article
(This article belongs to the Special Issue Advanced Technologies of Water and Wastewater Treatment (2nd Edition))
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26 pages, 8705 KB  
Article
Hydrochemical Characteristics and Formation Mechanism of Neogene Geothermal Water in the Zhangye–Minle Basin
by Zhen Zhang, Yang Hu, Tao Ren, Xiaodong Han and Xue Wu
Water 2025, 17(17), 2641; https://doi.org/10.3390/w17172641 - 6 Sep 2025
Viewed by 579
Abstract
Geothermal resources in arid inland basins are important for clean energy development, yet their circulation and geochemical mechanisms remain insufficiently understood. This study investigates the hydrochemical characteristics and formation mechanisms of geothermal water in the Zhangye–Minle Basin, an arid inland region in northwestern [...] Read more.
Geothermal resources in arid inland basins are important for clean energy development, yet their circulation and geochemical mechanisms remain insufficiently understood. This study investigates the hydrochemical characteristics and formation mechanisms of geothermal water in the Zhangye–Minle Basin, an arid inland region in northwestern China. A total of nine geothermal water samples were analyzed using major ion chemistry, stable isotopes (δ2H, δ18O), tritium (3H), and radiocarbon (14C) to determine recharge sources, flow paths, and geochemical evolution. The waters were predominantly of the Cl–Na and Cl·SO4–Na types, with total dissolved solids ranging from 3432.00 to 5810.00 mg/L. Isotopic data indicated that recharge originated from atmospheric precipitation and snowmelt in the Qilian Mountains, with recharge altitudes between 2497 and 5799 m. Tritium and 14C results suggested that most samples were recharged before 1953, with maximum ages exceeding 40,000 years. Gibbs diagrams and ion ratio plots demonstrated that water–rock interaction was the primary geochemical process, while cation exchange was weak. Na+ was mainly derived from halite, albite, and mirabilite, while SO42− originated largely from gypsum. The calculated reservoir temperatures using cation geothermometers ranged from 57 °C to 148 °C. The deep circulation of geothermal water was closely related to NNW-trending fault zones that facilitated infiltration and heat accumulation. These findings provide new insights into the recharge sources, circulation patterns, and geochemical processes of geothermal systems in fault-controlled basins, offering a scientific basis for their sustainable exploration and development. Full article
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18 pages, 1964 KB  
Article
Synthesis, Characterization, Antioxidant Activity, Antibacterial Activity, and Cytotoxicity of Quaternized Inulin Derivatives Bearing Aromatic Amides
by Yuan Chen, Yingqi Mi, Zhanyong Guo and Hongwu Zhang
Antioxidants 2025, 14(9), 1091; https://doi.org/10.3390/antiox14091091 - 6 Sep 2025
Viewed by 282
Abstract
In this study, a total of 12 new quaternized inulin (QIL) derivatives bearing aromatic amides were synthesized according to the ion exchange method. All the derivatives exhibited higher antioxidant activities in scavenging hydroxyl radicals, DPPH radicals, and superoxide radicals compared to pure inulin. [...] Read more.
In this study, a total of 12 new quaternized inulin (QIL) derivatives bearing aromatic amides were synthesized according to the ion exchange method. All the derivatives exhibited higher antioxidant activities in scavenging hydroxyl radicals, DPPH radicals, and superoxide radicals compared to pure inulin. Most of the derivatives could fully eliminate hydroxyl radicals at 1.6 mg/mL. Meanwhile, QIL derivatives exhibited increased antibacterial activity against Escherichia coli and Staphylococcus aureus compared to unmodified inulin. The structure–function relationship of the synthesized derivatives was discussed. Moreover, assays conducted with L929 cells (mouse fibroblasts) by the cell counting kit-8 (CCK-8) method did not show toxicities for the derivatives. Thus, the derivatives show promise for biomedical materials, functional foods, and pharmaceutical applications because they combine excellent antioxidant and antibacterial activities without exhibiting cytotoxicity. Full article
(This article belongs to the Section Natural and Synthetic Antioxidants)
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13 pages, 2422 KB  
Article
Luminescence of (YxGd3−x)(AlyGa5−y)O12:Ce and (LuxGd3−x)(AlyGa5−y)O12:Ce Radiation-Synthesized Ceramics
by Aida Tulegenova, Victor Lisitsyn, Gulnur Nogaibekova, Renata Nemkayeva and Aiymkul Markhabayeva
Ceramics 2025, 8(3), 112; https://doi.org/10.3390/ceramics8030112 - 5 Sep 2025
Viewed by 124
Abstract
(YxGd3−x)(AlyGa5−y)O12:Ce and (LuxGd3−x)(AlyGa5−y)O12:Ce ceramics were synthesized for the first time by direct exposure of a powerful electron flux to a mixture of the [...] Read more.
(YxGd3−x)(AlyGa5−y)O12:Ce and (LuxGd3−x)(AlyGa5−y)O12:Ce ceramics were synthesized for the first time by direct exposure of a powerful electron flux to a mixture of the corresponding oxide components. Five-component ceramics were obtained from oxide powders of Y2O3, Lu2O3, Gd2O3, Al2O3, Ga2O3, and Ce2O3 in less than 1 s, without the use of any additional reagents or process stimulants. The average productivity of the synthesis process was approximately 5 g/s. The reaction yield, defined as the mass ratio of the synthesized ceramic to the initial mixture, ranged from 94% to 99%. The synthesized ceramics exhibit photoluminescence when excited by radiation in the 340–450 nm spectral range. The position of the luminescence bands depends on the specific composition, with the emission maxima located within the 525–560 nm range. It is suggested that under high radiation power density, the element exchange rate between the particles of the initial materials is governed by the formation of an ion–electron plasma. Full article
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18 pages, 1655 KB  
Article
Pilot-Scale Evaluation of a Filter Prototype for Bacterial Inactivation in Agro-Food Processing Wastewater
by Piotr Kanarek, Barbara Breza-Boruta and Wojciech Poćwiardowski
Water 2025, 17(17), 2631; https://doi.org/10.3390/w17172631 - 5 Sep 2025
Viewed by 554
Abstract
The processing of freshly cut fruits and vegetables represents an important niche for implementing circular economy principles, particularly through the reuse of washing water. This is especially relevant as post-wash water is often treated as wastewater and discarded without reuse. One promising research [...] Read more.
The processing of freshly cut fruits and vegetables represents an important niche for implementing circular economy principles, particularly through the reuse of washing water. This is especially relevant as post-wash water is often treated as wastewater and discarded without reuse. One promising research avenue is the use of plant-derived extracts in water sanitation processes. Their antimicrobial properties offer a natural alternative to conventional disinfectants while reducing the formation of harmful disinfection by-products. The aim of this study was to evaluate the effectiveness of different filter bed configurations in removing pathogens from water. These configurations included a hydrogel saturated with natural plant extracts, an ion exchange resin layer, and an activated carbon layer. The most effective composite was also tested using real process water from a fruit washing line. The test materials included concentrated extracts from oak bark (Quercus robur), willow (Salix alba), birch (Betula pendula), raspberry shoots (Rubus idaeus), tea leaves (Camellia sinensis), and linden flowers (Tilia cordata), all immobilized in hydrogel, along with activated carbon and ion-exchange resin. Water samples were artificially inoculated with six opportunistic pathogens and collected process water was also used. Samples were analyzed microbiologically at six time intervals. The composite filter (hydrogel–resin–carbon) achieved a reduction of over 2 log10 in heavily inoculated water (~108 CFU mL−1) and maintained at least a 1 log10 reduction in real process effluents. The proposed solution supports blue water footprint reduction strategies (as the system aims to decrease the demand for freshwater resources through the reuse of treated wastewater) and aligns with the principles of green processing. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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23 pages, 3532 KB  
Article
Synthesis of Porous Materials on Hybrid Wormlike Micelles of Zwitterionic and Anionic Surfactants for Efficient Oilfield Wastewater Treatment
by Fei Liu, Zhenzhen Li, Chenye Yang, Ya Wu and Ying Tang
Gels 2025, 11(9), 714; https://doi.org/10.3390/gels11090714 - 5 Sep 2025
Viewed by 139
Abstract
Addressing the challenge of sulfonated lignite (SL) removal from oilfield wastewater, this study introduces a novel hierarchical MgFe-layered double hydroxide (LDH) adsorbent. The material was fabricated via in situ co-precipitation, utilizing a template formed by the NaCl-induced co-assembly of oleylaminopropyl betaine (OAPB) and [...] Read more.
Addressing the challenge of sulfonated lignite (SL) removal from oilfield wastewater, this study introduces a novel hierarchical MgFe-layered double hydroxide (LDH) adsorbent. The material was fabricated via in situ co-precipitation, utilizing a template formed by the NaCl-induced co-assembly of oleylaminopropyl betaine (OAPB) and sodium dodecyl sulfate (SLS) into zwitterionic, anionic, shear-responsive viscoelastic gels. This gel-templating approach yielded an LDH structure featuring a hierarchical pore network spanning 1–80 nm and a notably high specific surface area of 199.82 m2/g, as characterized by SEM and BET. The resulting MgFe-LDH demonstrated exceptional efficacy, achieving a SL removal efficiency exceeding 96% and a maximum adsorption capacity of 90.68 mg/g at neutral pH. Adsorption kinetics were best described by a pseudo-second-order model (R2 > 0.99), with intra-particle diffusion identified as the rate-determining step. Equilibrium adsorption data conformed to the Langmuir isotherm, signifying monolayer uptake. Thermodynamic analysis confirmed the process was spontaneous (ΔG < 0) and exothermic (ΔH = −20.09 kJ/mol), driven primarily by electrostatic interactions and ion exchange. The adsorbent exhibited robust recyclability, maintaining over 79% of its initial capacity after three adsorption–desorption cycles. This gel-directed synthesis presents a sustainable pathway for developing high-performance adsorbents targeting complex contaminants in oilfield effluents. Full article
(This article belongs to the Section Gel Analysis and Characterization)
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23 pages, 4980 KB  
Article
A Study on the Removal of Phosphate from Water Environments by Synthesizing New Sodium-Type Zeolite from Coal Gangue
by Yiou Wang, Qiang Li, Muyuan Ma, Zekun Xu and Tianhui Zhao
Water 2025, 17(17), 2628; https://doi.org/10.3390/w17172628 - 5 Sep 2025
Viewed by 540
Abstract
Excessive phosphorus emissions are a significant driver of severe eutrophication in water bodies, and developing an efficient and cost-effective adsorbent for phosphorus removal is imperative. In this study, a Na-type zeolite was synthesized from coal gangue sourced from an open-pit mine in Xinjiang [...] Read more.
Excessive phosphorus emissions are a significant driver of severe eutrophication in water bodies, and developing an efficient and cost-effective adsorbent for phosphorus removal is imperative. In this study, a Na-type zeolite was synthesized from coal gangue sourced from an open-pit mine in Xinjiang province, China. The synthesis process involved drying, crushing, alkali activation, aging, hydrothermal crystallization, and Na+ ion exchange. Orthogonal design identified the optimal synthesis parameters: an alkali-to-ash ratio of 1:1, aging at 20 °C for 12 h, and crystallization at 130 °C for 12 h. Aging time exerted the greatest influence on the phosphate removal efficiency. The optimized zeolite exhibited excellent phosphate adsorption performance, achieving a removal efficiency of up to 96% and a capacity of 16 mg/g. The adsorption kinetics followed both pseudo-first-order and pseudo-second-order models, indicating processes governed by combined physical and chemical mechanisms. Isotherm data fitting with Freundlich and Langmuir models suggested the presence of both homogeneous and heterogeneous active sites. Thermodynamic studies confirmed a spontaneous and endothermic process, increasingly favorable at higher temperatures. Characterizations via scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy confirmed the formation of Na-type zeolite and revealed structural and compositional changes following phosphate adsorption. Aluminum and calcium binding played key roles in the chemical adsorption mechanisms. This work not only offers a high-efficiency, low-cost solution for phosphorus removal from wastewater but also provides a sustainable pathway for the valorization of coal gangue in the Zhundong area of Xinjiang, China. Full article
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28 pages, 1495 KB  
Review
Low-Cost Adsorbents for the Removal of Pharmaceuticals from Surface Waters
by Erwin Onyekachukwu, Heather Nesbitt, Svetlana Tretsiakova-McNally and Heather Coleman
Water 2025, 17(17), 2619; https://doi.org/10.3390/w17172619 - 4 Sep 2025
Viewed by 671
Abstract
For decades, there has been increasing interest in pharmaceuticals’ prevalence in water bodies. This represents a major challenge in providing clean water, free from pharmaceutical contaminants, in different parts of the world. The misuse and overuse of pharmaceuticals, their elevated concentrations in surface [...] Read more.
For decades, there has been increasing interest in pharmaceuticals’ prevalence in water bodies. This represents a major challenge in providing clean water, free from pharmaceutical contaminants, in different parts of the world. The misuse and overuse of pharmaceuticals, their elevated concentrations in surface waters, and their negative impacts on humans, aquatic organisms, and ecosystems cannot be ignored. Significant efforts have been made toward the discovery of efficient water treatment techniques. Various technologies have been researched and applied, including co-precipitation, membrane separation, ion-exchange, oxidation, adsorption, and biochemical processes. Amidst these technologies, adsorption is considered a promising due to its unique advantages. This review discusses the pharmaceuticals that have been detected in surface waters in concentrations ranging from ng/L to μg/L. It also offers insights into the diverse applications of low-cost adsorbents to deal with pharmaceutical water pollutants and various parameters influencing the adsorption process. This article will assist in promoting the utilization of sustainable, low-cost adsorbents with high adsorption efficiencies in the water treatment process, and it will aid environmentalists in devising strategies for anticipated challenges and provide policymakers with valuable guidance. Full article
(This article belongs to the Section Water Quality and Contamination)
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19 pages, 2878 KB  
Article
Exploration of Methods for In Situ Scale Removal During Magnesium Hydroxide Membrane Crystallization
by Ester Komačková, Lukáš Sedlák, Ivan Červeňanský and Jozef Markoš
Membranes 2025, 15(9), 267; https://doi.org/10.3390/membranes15090267 - 3 Sep 2025
Viewed by 258
Abstract
In coastal countries facing a shortage of drinking water, seawater desalination is essential for the production of potable water. During desalination, a large volume of waste stream, known as brine, is generated. This stream contains high concentrations of salts, particularly those of economic [...] Read more.
In coastal countries facing a shortage of drinking water, seawater desalination is essential for the production of potable water. During desalination, a large volume of waste stream, known as brine, is generated. This stream contains high concentrations of salts, particularly those of economic importance to the European Union, such as magnesium and calcium. By further processing this stream, these materials can be recovered. One method studied for separating magnesium from wastewater is membrane crystallization (MCr). The MCr process developed in this work utilizes ion-exchange membranes that separate the model brine solution from a precipitating agent, which is a solution of sodium hydroxide. During the process, the membrane allows the transport of anions between the two solutions, enabling the reaction between OH anions and Mg2+ cations, which leads to the formation of a magnesium hydroxide precipitate. The formed precipitate can then be filtered out of the brine solution, which now has decreased salinity due to crystallization facilitated by the ion-exchange membrane. However, precipitation occurs near the membrane surface, resulting in the deposition of magnesium hydroxide onto the outer surface of the membrane. The aim of this study is to investigate methods for effectively removing magnesium hydroxide from the membrane surface, with a primary focus on maximizing the yield of magnesium hydroxide crystals in suspension. Crystal removal was induced by circulation of hydrochloric acid, followed by circulation of demineralized water through the membrane module after crystallization. In this study, a membrane module made of hollow-fiber anion-exchange membranes was employed. The production cost of these membranes is approximately 50% lower per square meter compared to flat-sheet membranes commonly used in electrodialysis, demonstrating strong potential for commercial application. More than 85% magnesium conversion was achieved during the process, yet the majority of the crystals remained attached to the membrane. Circulation of hydrochloric acid and demineralized water after the crystallization process caused detachment of the crystals into suspension, nearly doubling their yield. Full article
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16 pages, 6160 KB  
Article
Synthesis of RuO2-Co3O4 Composite for Efficient Electrocatalytic Oxygen Evolution Reaction
by Jingchao Zhang, Yingping Bu, Jia Hao, Wenjun Zhang, Yao Xiao, Naihui Zhao, Renchun Zhang and Daojun Zhang
Nanomaterials 2025, 15(17), 1356; https://doi.org/10.3390/nano15171356 - 3 Sep 2025
Viewed by 415
Abstract
Among various H2 production methods, splitting water using renewable electricity for H2 production is regarded as a promising approach due to its high efficiency and zero carbon emissions. The oxygen evolution reaction (OER) is an important part of splitting water, but [...] Read more.
Among various H2 production methods, splitting water using renewable electricity for H2 production is regarded as a promising approach due to its high efficiency and zero carbon emissions. The oxygen evolution reaction (OER) is an important part of splitting water, but also the main bottleneck. The anodic oxygen evolution reaction (OER) for water electrolysis technology involves multi-electron/proton transfer and has sluggish reaction kinetics, which is the key obstacle to the overall efficiency of electrolyzing water. Therefore, it is necessary to develop highly efficient and cheap OER electrocatalysts to drive overall water splitting. Herein, a series of efficient RuO2-Co3O4 composites were synthesized via a straightforward three-step process comprising solvothermal synthesis, ion exchange, and calcination. The results indicate that using 10 mg of RuCl3·xH2O and 15 mg of Co-MOF precursor in the second ion exchange step is the most effective way to acquire the Co3O4-RuO2-10 (RCO-10) composite with the largest specific area and the best electrocatalytic performance after the calcination process. The optimal Co3O4-RuO2-10 composite powder catalyst displays low overpotential (η10 = 272 mV), a small Tafel slope (64.64 mV dec−1), and good electrochemical stability in alkaline electrolyte; the overall performance of Co3O4-RuO2-10 surpasses that of many related cobalt-based oxide catalysts. Furthermore, through integration with a carbon cloth substrate, Co3O4-RuO2-10/CC can be directly used as a self-supporting electrode with high stability. This work presents a straightforward method to design Co3O4-RuO2 composite array catalysts for high-performance electrocatalytic OER performance. Full article
(This article belongs to the Special Issue Nanomaterials for Sustainable Green Energy)
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18 pages, 2222 KB  
Article
Experimental Study on the Evolution Law of Pb in Soils and Leachate from Rare Earth Mining Areas Under Different Leaching Conditions
by Zhongqun Guo, Shaojun Xie, Feiyue Luo, Qiangqiang Liu and Jun Zhang
Earth 2025, 6(3), 103; https://doi.org/10.3390/earth6030103 - 3 Sep 2025
Viewed by 302
Abstract
In the exploitation of ion-adsorption rare earth ores, the environmental effects of leaching agents are key constraints for green mining. Understanding the release behavior of typical heavy metals from soils under leaching conditions is of great significance. Laboratory column leaching experiments were conducted [...] Read more.
In the exploitation of ion-adsorption rare earth ores, the environmental effects of leaching agents are key constraints for green mining. Understanding the release behavior of typical heavy metals from soils under leaching conditions is of great significance. Laboratory column leaching experiments were conducted to systematically investigate the effects of three leaching agents—(NH4)2SO4, Al2(SO4)3, and MgSO4—as well as varying concentrations of Al2(SO4)3 on the release and speciation transformation of heavy metal Pb in mining-affected soils. The results revealed a three-stage pattern in Pb release—characterized by slow release, a sharp increase, and eventual stabilization—with environmental risks predominantly concentrated in the middle to late stages of leaching. Under 3% (NH4)2SO4 and 3% Al2(SO4)3 leaching conditions, Pb concentrations in soil increased significantly, with a higher proportion of labile fractions, indicating pronounced activation and risk accumulation. Due to its relatively weak ion-exchange capacity, MgSO4 exhibited a lower and more gradual Pb release profile, posing substantially lower pollution risks compared to (NH4)2SO4 and Al2(SO4)3. Pb release under varying Al2(SO4)3 concentrations showed a nonlinear response. At 3% Al2(SO4)3, both the proportion of bioavailable Pb and the Risk Assessment Code (RAC) peaked, while the residual fraction declined sharply, suggesting a threshold effect in risk induction. All three leaching agents promoted the transformation of Pb in soil from stable to more labile forms, including acid-soluble, reducible, and oxidizable fractions, thereby increasing the overall proportion of active Pb (F1 + F2 + F3). A combined analysis of RAC values and the proportion of active Pb provides a comprehensive framework for assessing Pb mobility and ecological risk under different leaching conditions. These findings offer a theoretical basis for the prevention and control of heavy metal risks in the green mining of ion-adsorption rare earth ores. Full article
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24 pages, 6589 KB  
Article
Beyond Fossil Fuels: The Role of V-Doped Hydrotalcites in n-Butane Oxidative Dehydrogenation for a Circular Economy
by Agnieszka Węgrzyn, Alicja Katarzyńska, Paweł Miśkowiec and Wacław Makowski
Catalysts 2025, 15(9), 841; https://doi.org/10.3390/catal15090841 - 2 Sep 2025
Viewed by 458
Abstract
This study explores the catalytic performance of V3+-modified Mg/Al hydrotalcite-derived materials in the oxidative dehydrogenation (ODH) of n-butane, compared with catalysts derived from pyrovanadate and decavanadate precursors. Different methods for preparing hydrotalcite-like materials were applied to obtain vanadium-containing Mg-Al mixed oxide [...] Read more.
This study explores the catalytic performance of V3+-modified Mg/Al hydrotalcite-derived materials in the oxidative dehydrogenation (ODH) of n-butane, compared with catalysts derived from pyrovanadate and decavanadate precursors. Different methods for preparing hydrotalcite-like materials were applied to obtain vanadium-containing Mg-Al mixed oxide catalysts for n-butane ODH. The hydrotalcite-like precursors were doped with vanadates (V5+) via ion exchange or co-precipitation or with V3+ cations incorporated into brucite-like layers. During calcination in air or argon flow, different vanadium-containing phases were obtained. Our findings demonstrate that V3+-doped hydrotalcites exhibit superior activity and selectivity toward the total C4H8 products, with enhanced selectivity for 1,3-butadiene. The highest n-butane conversion was observed for catalysts with an MgO structure and vanadium dispersed in the oxide matrix. A similar conversion level (~44%) was obtained for a spinel-like Mg2VO4 catalyst, but only a 15% level was found for the highly crystalline α-Mg2V2O7 catalyst. In contrast, the highest selectivities toward dehydrogenated products were observed for V3+-containing and α-Mg2V2O7 catalysts. NH3- and CO2-temperature programmed desorption (TPD) analyses showed that high basicity combined with low acidity favors the formation of butene isomers and 1,3-butadiene. This work highlights the strategic potential of tailoring vanadium speciation and hydrotalcite-based catalyst design for low-carbon chemical manufacturing, supporting the transition toward a circular economy. Full article
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